Anniversary Paper: Past and current issues, and trends in brachytherapy physics

Abstract

Brachytherapy began at the turn of the 20th century, contemporary with external-beam radiotherapy. Physicists and physicians together developed the field. There has not been a period since the beginning that has not witnessed innovations and progress in brachytherapy. At the time of this article, the pace of change in the field has never been more rapid, particularly in image-guided brachytherapy and the development of unconventional sources and treatment techniques.

Current state of the art brachytherapy treatment planning dosimetry algorithms

“…Literature on the effect of tissue composition heterogeneities in the energy range of 125 I and 103 Pd has been recently reviewed. 6,7 Average elemental composition cannot, however, be obtained through routine clinical imaging methods, with promising alternatives such as dual energy or spectral CT requiring further research. 6 The m en /m ratio plotted in the inset of Figure 1 vs energy quantifies the average energy absorbed per interaction.…”

“…In the past decade, brachytherapy has progressed from the traditional surgical paradigm to modern three-dimensional (3D) image-based treatment planning systems (TPSs) and dose delivery. The information available through patient imaging, however, had not been fully exploited since TG43-based dosimetry relies on sourcespecific data pre-calculated in a standard homogeneous water geometry.1-3 Hence, it disregards patient-specific radiation scatter conditions and the radiological differences of tissue or applicator materials from water.In response to literature on the effect of these shortcomings, which has been reviewed in several recent publications, [4][5][6][7] TPSs have become commercially available that include improved dosimetry algorithms, collectively referred to as model-based dosimetry algorithms (MBDCAs). At the time of writing, these include a deterministic solver of the linear Boltzmann transport equation (LBTE) 8-10 and a collapsed cone superposition (CCS) algorithm 11-17 for 192 Ir high-doserate (HDR) applications.…”

“…In response to literature on the effect of these shortcomings, which has been reviewed in several recent publications, [4][5][6][7] TPSs have become commercially available that include improved dosimetry algorithms, collectively referred to as model-based dosimetry algorithms (MBDCAs). At the time of writing, these include a deterministic solver of the linear Boltzmann transport equation (LBTE) [8][9][10] and a collapsed cone superposition (CCS) algorithm 11-17 for 192 Ir high-doserate (HDR) applications.…”

Dosimetric audit in brachytherapy

“…29,30,31 The pace of change in brachytherapy equipment, physics and clinical processes has also been rapid in recent years with the integration of multimodality 3D imaging, improved dosimetry and treatment planning including patientspecific optimization, volume prescribing and new equipment and applicators. [32][33][34] Treatment planning algorithms in brachytherapy might also be on the verge of a step change in complexity and a move from standard planning to fully flexible optimization might have widespread uptake. [32][33][34][35] To contribute to the overall quality, safety and reassurance, brachytherapy should be subjected to the same rigour of local quality checks 36 and audit mechanisms as external beam radiotherapy.…”

PDT is better than alternative therapies such as brachytherapy, electron beams, or low‐energy x rays for the treatment of skin cancers

“…6,7 The development of artificial radionuclides and remote afterloading devices has made this procedure safe for both the patient and the delivering personnel. In external beam therapies, megavoltage electrons are gradually replacing superficial x rays in treatment of skin cancers.…”